322 THE CANADIAN ENTOMOLOGIST 



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of experimenters in the United States scalecide (a miscible oil) 

 was used both in the Wentworth and Norfolk orchards. Fairly 

 good results were obtained in both orchards, but as this mixture 

 is costly it was used only one season in the Wentworth orchard 

 and two seasons in the Norfolk one. It was then thought that 

 natural agents would probably furnish the work of control and 

 that the insect would gradually disappear. This proved true in 

 th,e case of the Wentworth orchard just as it had done in the 

 Northumberland, but failed in the Norfolk. It is interesting, 

 therefore, to know that in one locality, even apart from any effec- 

 tive spray, natural foes — parasites, disease and unfavourable 

 weather — were able in a few years to remove or control a very 

 dangerous pest, and that in another district they failed to do so 

 even though aided by an application of one of the most effective 

 sprays known. The explanation probably lies in the fact that 

 there is considerable difference in climate in winter, spring and 

 autumn between Norfolk and Northumberland Counties, and also 

 to a lesser extent between Norfolk and Wentworth Counties. 

 Our studies in Norfolk showed that there were at least two 

 species of dipterous parasites there and four or five species of 

 hymenopterous parasites; so that the persistence of the Leaf- 

 rollers there was not due to the absence of parasites, though cooler 

 weather during the larval stages of the insect may have pre- 

 vented the parasites from being so active as in the other orchards. 

 This, however, is by no means certain. 



Lest fruit growers finding a few rolled leaves with greenish or 

 yellowish green larvae in them become alarmed and think that 

 they are going to have an attack of this dangerous pest, we may 

 mention that there is another very common Leaf-roller, known as 

 the oblique-banded Leaf -roller which occurs almost every year in 

 small numbers in almost every orchard. The larva of this species 

 is not easily distinguished from its more dangerous relative and, 

 therefore, may easily be mistaken for it. The adult moths, how- 

 ever, are easily distinguished. The- proper course in our opinion 

 for fruit growers to pursue is not to worry about the Fruit-tree 

 Leaf-roller until it is known to be present in the orchard and to 

 be doing considerable damage- — enough damage to justify special 

 measures. When this state of affairs exists spray the trees very 



